# US 5,705,368 A · Process for preparation of purified xanthan gum

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- Number: US 5,705,368 A
- Document ID: US5705368A
- Status: Granted
- Kind: A
- Application number: 07/990,758
- Filed: 1992-12-15
- Granted: 1998-01-06
- Earliest claimed: 1991-12-20
- Assignees: Shin-Etsu Chemical Co., Ltd.; Shin-Etsu Bio, Inc.
- Inventors: Kanji Murofushi; Taira Homma; Shigehiro Nagura; Richard Armentrout
- Web page: https://patentgrep.com/patent/US5705368A

## CPC

- C12P 19/06: Xanthan, i.e. Xanthomonas-type heteropolysaccharides
- C08B 37/0033: {Xanthan, i.e. D-glucose, D-mannose and D-glucuronic acid units, saubstituted with acetate and pyruvate, with a main chain of (beta-1,4)-D-glucose units; Derivatives thereof}
- Y10S 435/822: using bacteria or actinomycetales
- Y10S 435/91: Xanthomonas
- Y10S 530/813: Carrier is a saccharide
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The process comprises heat-treating a xanthan gum fermented broth, and consecutively treating the broth first with alkaline protease and then with lysozyme or in reverse order, and thereafter recovering xanthan gum from the treated broth. A clear aqueous solution of xanthan gum may be obtained without complex procedures.

## Claims

### Claim 1

In a process for the preparation of xanthan gum wherein Xanthomonas campestris bacteria are subjected to fermentation in a broth to produce a fermented broth containing xanthan gum, the improvement which comprises:
a) heating the fermented broth at a temperature from 45.degree. to 70.degree. C. for a period of at least 30 minutes at an initial pH of 9 to 12.5;
b) contacting the heated broth from step a) with an alkaline protease for a period of from 20 minutes to five hours at a temperature of 40.degree. to 65.degree. C. and a pH of 6.0 to 10.0;
c) contacting the broth from step b) with lysozyme for a period of from 20 minutes to five hours at a temperature of 25.degree. to 45.degree. C. and a pH of 5.5 to 8.0; and
d) recovering the xanthan gum from the broth from step c).

### Claim 2

In a process for the preparation of xanthan gum wherein Xanthomonas campestris bacteria are subjected to fermentation in a broth to produce a fermented broth containing xanthan gum, the improvement which comprises:
a) heating the fermented broth at a temperature from 45.degree. to 70.degree. C. for a period of at least 30 minutes at an initial pH of 9 to 12.5;
b) contacting the broth from step a) with lysozyme for a period of from 20 minutes to five hours at a temperature of 25.degree. to 45.degree. C. and a pH of 5.5 to 8.0;
c) contacting the broth from step b) with an alkaline protease for a period of from 20 minutes to five hours at a temperature of 40.degree. to 65.degree. and a pH of 6.0 to 10.0; and
d) recovering the xanthan gum from the broth from step c).

### Claim 3 (depends on 1)

The process as claimed in claim 1, wherein the contacting with the alkaline protease is carried out with the addition of 10 to 500 ppm of the alkaline protease to the xanthan gum fermented broth, at a temperature of 40.degree. to 65.degree. C. and a pH of 6.0 to 10.0 for at least 30 minutes.

### Claim 4 (depends on 2)

The process as claimed in claim 2, wherein the contacting with the alkaline protease is carried out with the addition of 10 to 500 ppm of the alkaline protease to the xanthan gum fermented broth, at a temperature of 40.degree. to 65.degree. C. and a pH of 6.0 to 10.0 for at least 30 minutes.

### Claim 5 (depends on 1)

The process as claimed in claim 1, wherein the contacting with the lysozyme is carried out with the addition of 0.5 to 100 ppm of the lysozyme to the fermented broth of xanthan gum, at a temperature of 25.degree. to 45.degree. C. and a pH of 5.5 to 8.0 for at least 30 minutes.

### Claim 6 (depends on 2)

The process as claimed in claim 2, wherein the contacting with the lysozyme is carried out with the addition of 0.5 to 100 ppm of the lysozyme to the fermented broth of xanthan gum, at a temperature of 25.degree. to 45.degree. C. and a pH of 5.5 to 8.0 for at least 30 minutes .